Re: Trying to understand a simple piece of code: dmd barray

[Dibyendu Majumdar via Digitalmars-d-learn]

On Saturday, 7 March 2020 at 14:33:29 UTC, Steven Schveighoffer 
wrote:


It's D's version of implicit conversion.

You can make the alias this a no-arg function and it will try 
calling that function.




Okay thank you.

Re: Trying to understand a simple piece of code: dmd barray

[Ferhat Kurtulmuş via Digitalmars-d-learn]

On Saturday, 7 March 2020 at 13:06:39 UTC, Dibyendu Majumdar 
wrote:

On Saturday, 7 March 2020 at 12:26:32 UTC, drug wrote:

I am trying to understand 
https://github.com/dlang/dmd/blob/master/src/dmd/backend/barray.d.


Two questions:

1. What does this mean and why is it needed?

line 95: alias array this;


This means that `array` can be used instead of `this`


Hmm should not that change the meaning of this throughout the 
struct? is this good practice?


Thank you


This is also a way of imitating inheritance in c-ish code without 
classes.

Re: Trying to understand a simple piece of code: dmd barray

[Steven Schveighoffer via Digitalmars-d-learn]

On 3/7/20 8:06 AM, Dibyendu Majumdar wrote:

On Saturday, 7 March 2020 at 12:26:32 UTC, drug wrote:

I am trying to understand 
https://github.com/dlang/dmd/blob/master/src/dmd/backend/barray.d.


Two questions:

1. What does this mean and why is it needed?

line 95: alias array this;


This means that `array` can be used instead of `this`


Hmm should not that change the meaning of this throughout the struct? is 
this good practice?


No, it's simply a fallback. If the symbol doesn't work with this.symbol, 
try this.array.symbol.


It's D's version of implicit conversion.

You can make the alias this a no-arg function and it will try calling 
that function.


-Steve

Re: Trying to understand a simple piece of code: dmd barray

[Dibyendu Majumdar via Digitalmars-d-learn]

On Saturday, 7 March 2020 at 12:26:32 UTC, drug wrote:

I am trying to understand 
https://github.com/dlang/dmd/blob/master/src/dmd/backend/barray.d.


Two questions:

1. What does this mean and why is it needed?

line 95: alias array this;


This means that `array` can be used instead of `this`


Hmm should not that change the meaning of this throughout the 
struct? is this good practice?


Thank you

Re: Trying to understand a simple piece of code: dmd barray

[Steven Schveighoffer via Digitalmars-d-learn]

On 3/7/20 7:26 AM, drug wrote:

07.03.2020 15:05, Dibyendu Majumdar пишет:

Hi,

I am trying to understand 
https://github.com/dlang/dmd/blob/master/src/dmd/backend/barray.d.


Two questions:

1. What does this mean and why is it needed?

line 95: alias array this;


This means that `array` can be used instead of `this`


To expand on this, the compiler basically substitutes the symbol aliased 
here for the item itself if all other members are a compiler error.


So for example, if you have:

barr.length;

and barr has no member length, it tries:

barr.array.length

-Steve

Re: Trying to understand a simple piece of code: dmd barray

[drug via Digitalmars-d-learn]

07.03.2020 15:05, Dibyendu Majumdar пишет:

Hi,

I am trying to understand 
https://github.com/dlang/dmd/blob/master/src/dmd/backend/barray.d.


Two questions:

1. What does this mean and why is it needed?

line 95: alias array this;


This means that `array` can be used instead of `this`
2. The struct has no property called length - but this is referenced. 
Where does this come from?

it comes from `array` being alias for `this`, see above


Thank you

Regards

Trying to understand a simple piece of code: dmd barray

[Dibyendu Majumdar via Digitalmars-d-learn]

Hi,

I am trying to understand 
https://github.com/dlang/dmd/blob/master/src/dmd/backend/barray.d.


Two questions:

1. What does this mean and why is it needed?

line 95: alias array this;

2. The struct has no property called length - but this is 
referenced. Where does this come from?


Thank you

Regards